Mexican Federal police block the road between the northern cities of Monterrey and Reynosa on May 13, 2012. At least 37 mutilated bodies were found dumped in black plastic bags near the northern Mexico city of Monterrey, law enforcement officials said Sunday, in an apparent flare up of brutal drug violence. Photo: AFP

A spokesperson for the state of Nuevo Leon told AFP that 49 bodies had been counted after their discovery on an isolated stretch of a highway 180 kilometers (110 miles) from the US border.

The find comes just days after police discovered the dismembered, decapitated bodies of 18 people in two abandoned vehicles in western Mexico, in what appeared to be a revenge killing involving powerful drug gangs.

Just a few days earlier, there were 23 killings in the city of Nuevo Laredo, in Tamaulipas state which borders the United States, comprising nine people found hanging from a bridge and 14 others that had been decapitated.

Suspected drug gang violence has risen across the country this month, with scores of deaths attributed to massacres and clashes with security forces.

Authorities have blamed much of the deadly violence on battles between the Zetas -- a gang set up by ex-commandos that deserted in the 1990s -- and groups allied to the Sinaloa Federation of Mexico's most wanted drug lord, Joaquin "El Chapo" Guzman.